Apparatus for heating fluids

ABSTRACT

The present invention relates to an improved fluid heater apparatus of the type having walls defining a furnace space, a plurality of heating tubes passing through the furnace space and one or more high intensity combustion burners attached to and positioned with respect to the furnace space so that combustion gases are directed under super-atmospheric pressure into the furnace space and circulated around the heating tubes thereby causing the transfer of heat to the fluid being heated. By the present invention walls defining a secondary furnace space, a second plurality of heating tubes and means connecting between the primary and secondary furnace spaces are provided so that spent combustion gases from the primary furnace space flow through the secondary furnace space under super-atmospheric pressure and additional heat is transferred from the spent combustion gases to the fluid being heated.

Waite States Ptet 1 Ebeling et al.

[ 5] Feb. 12, 1974 APPARATUS FOR HEATING FLUIDS [75] Inventors: Harold O. Ebeling; Richard A.

Beets, both of Oklahoma City, Okla.

[73] Assignee: Black, Sivalls & Bryson, lnc.,

Oklahoma City, Okla.

[22] Filed: Aug. 3, 1972 [21] Appl. No.: 277,682

[52] US. Cl. 122/356, 122/23 7/196] Thurley 122/23 Primary Examiner-Kenneth W. Sprague Attorney, Agent, or FirmC. Clark Dougherty, .lr.; Jerry J. Dunlap; Dunlap, Laney, Hessin & Dougherty [57] ABSTRACT The present invention relates to an improved fluid heater apparatus of the type having walls defining a furnace space, a plurality of heating tubes passing through the furnace space and one or more high intensity combustion burners attached to and positioned with respect to the furnace space so that combustion gases are directed under super-atmospheric pressure into the furnace space and circulated around the heating tubes thereby causing the transfer of heat to the fluid being heated. By the present invention walls defining a secondary furnace space, a second plurality of heating tubes and means connecting between the primary and secondary furnace spaces are provided so that spent combustion gases from the primary furnace space flow through the secondary furnace space under super-atmospheric pressure and additional heat is I transferred from the spent combustion gases to the fluid being heated.

7 Claims, 5 Drawing Figures sum 1 0F 2 PAIENTED FEB I 2 PAIENIE FEB'I 2 I974 SHEET 2 BF 2 [a L M FUEL 6,4 I 4 w M. l

a M, @WW E W M COM5U5770/V 4 FUEL 6,45

l q. L5

directed APPARATUS FOR HEATING FLUIDS BACKGROUND OF THE INVENTION 1. Field of the Invention 'The present invention relates generally to fluid heater apparatus, and more particularly, but not by way of limitation, to improved fluid heater apparatus of the type wherein one or more high intensity combustion burners are utilized and the combustion gases produced thereby are recirculated within a furnace space.

2. Background of the Invention A great variety of fluid heater apparatus have been developed and used successfully. One such heater which has proven to be particularly useful in the oil, chemical and other industries for heating various types of fluids is described and claimed in US. Pat. Nov 2,993,479. This type of heater is basically comprised of a wall structure forming a furnace space which contains a plurality of heating tubes and one or more high intensity combustion burners are connected to a wall of the furnace space. High intensity burners are characterized in that complete combustion takes place within the combustion chambers of the burners, and as a result,

the burners can be mounted in direct combustion with the furnace space since no flame is ejected from the burners into the furnace space. An air blower is utilized with the burners so that the products of combustion formed in the combustion chambers of the burners are into the furnace space under superatmospheric pressure and are recirculated around the heating tubes in a manner such that even heating of the tubes and the fluid passing therethrough results. The term high intensity combustion burner is used here to mean any burner apparatus or burner apparatus in combination with one or more air or combustion gas blowers which is capable of producing hot combustion gases at a relatively high velocity under superatmospheric pressure. The recirculation of the hot combustion gases may be either internal or external of the furnace space and a blower may be utilized to facilitate such recirculation.

By the present invention, an improved fluid heater apparatus of the type described above is provided wherein spent combustion gases exiting from the furnace space are caused to flow under super-atmospheric pressure through a secondary furnace space whereby additional heat is transferred from the combustion gases to the fluid being heated.

I SUMMARY OF THE INVENTION The present invention relates to a fluid heater apparatus comprising walls defining a primary furnace space having a spent combustion gas outlet therein. A plurality of heating tubes are disposed within the primary furnace space, and at least one high intensity combustion burner is attached and positioned with respect to the primary furnace space so that combustion gases produced by the burner or burners are directed under super-atmospheric pressure into the furnace space and recirculated around the heating tubes. Walls defining a secondary furnace space having combustion gas inlet and outlet connections therein are provided and a second plurality of fluid heating tubes-are disposed within the secondary furnace space. Conduit means are provided connecting the heating tubes disposed within the primary and secondary furnace spaces so that the fluid being heated flows through the heating tubes within the primary furnace space and then through the heating tubes disposed within the secondary furnace space. Means connecting between the spent combustion gas outlet of the primary furnace space and the combustion gas inlet of the secondary furnace space are provided so that spent combustion gases from the primary furnace space flow under super-atmospheric pressure through the secondary furnace space and additional heat is transferred from the spent combustion gases to the fluid being heated.

It is, therefore, an object of the present invention to provide an improved fluid heater apparatus.

A further object of the present invention is the provision of an improved heater apparatus of the type wherein combustion gases are recirculated within a furnace space wherein a maximum utilization of the heat content of the combustion gases is realized.

Yet a further object of the present invention is the provision of an improved heater apparatus including a secondary heat recovery furnace space where the secondary furnace space may readily be added to or removed from the apparatus as desired.

Other and further'objects of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments of the invention which follows when taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of one form of the improved heater apparatus of the present invention.

FIG. 2 is a side elevational view of the apparatus of FIG. 1 partially in section.

FIG. 3 is a plan view of the apparatus of FIG. 1.

FIG. 4 is a diagrammatic view of the heater apparatus of FIG. 1.

FIG. 5 is a diagrammatic view of an alternate form of the improved heater apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and particularly to FIGS. 1 through 3 the improved fluid heater apparatus of the present invention is illustrated and generally designated by the numeral 10. The apparatus 10 is basically comprised of a primary furnace space 11 formed by a plurality of walls 12. Attached to one of the walls 12, preferably the lower wall or floor, are one or more high intensity combustion burners It. Each of the burners 14 includes a fuel gas inlet 15 which is connnected to a source of fuel gas by a fuel gas manifold (not shown) and a source of combustion air, generally comprised of one or more combustion air blowers, is connected to combustion air inlet connections 16 of the burners 14 by a combustion air manifold (not shown).

A plurality of heating tubes 18 (FIG. 2) are disposed within the primary furnace space 11. Preferably, the heating tubes 18 are divided into a pair of tube banks each of which includes an inlet connection 20 and an outlet connection 22 passing through one of the side walls 12 of the primary furnace space 11. Stated another way and as best shown diagrammatically in FIG. 4, the heating tubes 18 are preferably divided into two parallel flow tube banks 19 and 21 positioned on opposite sides of the furnace space 1 1. The furnace space 1 1 includes a pair of combustion gas outlet connections 24, positioned in the lower portion of opposite walls 12 thereof.

A secondary furnace space 25 is provided formed by a plurality of walls 26. The secondary furnace space 25 includes a plurality of heating tubes 28 (FIG. 2) disposed therein. Preferably, the heating tubes 28 are comprised of a pair of parallel heating tube banks each connected to an inlet connection 30 passing through one of the walls 26 and an outlet connection 32 passing through an opposite wall 26. The secondary furnace space 25 includes a pair of combustion gas inlet connections 34 on opposite walls 26 thereof, each of which are connected to one of the combustion gas outlet connections 24 disposed in the walls 12 of the primary furnace space 11 by a conduit 36. The secondary furnace space 25 also includes a plurality of combustion gas outlet connections 38, each of which has a stack 40 connected thereto.

Operation of the Apparatus Referring now to FIG. 4 the fluid heater apparatus 10 is illustrated diagrammatically. In operation of apparatus l0, combustion air and fuel gas are supplied to the high intensity burners 14 so that combustion gases are produced and directed into the primary furnace space 1 1 under super-atmospheric pressure. As will be understood by those skilled in the art, conventional instruments and controls are utilized to regulate the flow of fuel gas and combustion air to the burners 14 so that substantially stoichiometric quantities thereof are combusted and so that the desired quantity of heat is transferred to the fluid being heated. Due to the relatively high velocity imparted to the combustion gases by the burners 14 and the physical arrangement of the burners 14 with respectto the heating tubes 18 and primary furnace space 11, the combustion gases recirculate within the primary furnace space 1 1 around the heating tubes 18 as illustrated by the arrows in FIG. 4. Due to this recirculating of combustion gases within the primary furnace space 11, even heating of the heating tubes and fluid being heated takes place thereby obviating problems associated with hot spots, etc.

As can be best seen in H65. 1 through 3, the fluid being heated is conducted by way of the inlet connections 20 through the parallel banks 19 and 21 of heating tubes 18 disposed within the primary space 11, out of the primary furnace space 11 by way of the outlet connections 22, and finally through the heating tubes 28 disposed within the secondary furnace space by way of the conduits 23, inlet connections 30 and outlet connections 32. While the heater apparatus 10 has been described having parallel tube banks, it will be understood by those skilled in the art that any of a variety of series and/or parallel heating tube arrangements can be utilized. The particular heating tube arrangement which should be used for a particular application of the fluid heater apparatus 10 is determined by conventional engineering design and economic considerations.

After the combustion gases produced by the burners 14 recirculate through the primary furnace space 11, they exit the furnace space 11 by way of the combustion gas outlet connections 24 disposed in opposite walls 12 thereof. The combustion gases flow by way of the conduits 36 and inlet connections 34 into the secondary furnace space 25 and while passing therethrough, additional heat is transferred from the combustion gases through the walls of the heating tubes 28 disposed therein to the fluid being heated. The resulting spent combustion gases exit the secondary furnace space 25 by way of the outlet connections 38 and stacks 40 connected thereto.

Because the combustion gases are directed into the primary furnace space 11 under super-atmospheric pressure, the driving force required for causing the combustion gases to flow through the conduits 36 and through the secondary furnace space 25 is available. The improved fluid heater apparatus 10 brings about highly efficient fluid heating in that a maximum utilization of the heat content of the combustion gases produced by the high intensity combustion burners 14 is transferred to the fluid being heated. A further advantage of the heater apparatus 10 is that the secondary furnace space 25 may be added to an exiting fluid heater of the type herein described to increase the thermal efficiency thereof, or when it is necessary to change the location of such a heater apparatus, the secondary furnace space 15 may or may not be utilized as dictated by design and economic considerations.

Referring now to FIG. 5,an alternate form of the improved fluid heater apparatus of the present invention is illustrated diagrammatically and generally designated by the numeral 41. In this form of the invention instead of a single secondary furnace space, a pair of secondary furnace spaces 42 and 44 are provided, each of which is removably attached to an opposite wall 43 of the primary furnace space 45. The primary furnace space includes heating tubes 47 disposed therein and one or more high intensity combustion burners 49 attached thereto. The arrangement of parts and the operation of the primary furnace space 45 and the high intensity combustion burners 49 are identical to that described above in connection with the heater apparatus 10 (PK). 4). However, the combustion gases exit the primary furnace space 45 by way of a plurality of openings disposed in opposite walls 43 thereof. Each of the secondary furnace spaces 42 and 44 include openings in a wall thereof which are complimentary to the openings 50 so that spent combustion gases from the primary furnace space 45 pass through the openings 50 into the secondary furnace spaces 40 and 42. Heating tubes 46 are disposed within the secondary furnace space 42 and heating tubes 48 are disposed within the secondary furnace space 44. The heating tubes 46 and 48 are connected to the heating tubes 47 disposed within the primary furnace space 45 so that the fluid being heated passes through the heating tubes 46 and 48 after passing through the heating tubes 47. As the combustion gases exiting the primary furnace space 45 pass through the secondary furnace spaces 42 and 44respectively, additional heat is transferred from the combustion gases to the fluid being heated thereby bringing about the utilization of a maximum quantity of the heat content of the combustion gases. The secondary furnace spaces 42 and 44 are preferably removably attached to the primary furnace space 45 so that they may be readily removed. As described above in connection with the apparatus 10, the combustion gases flow through the primary furnace space 45 and the secondary furnace spaces 42 and 44 under super-atmospheric pressure which brings about and allows the transfer of a maximum quantity of heat from the combustion gases to the fluid being heated. Specifically, the heat transfer within the primary furnace space 45 is improved as compared to a heater apparatus without the secondary furnace spaces-42 and 44 attached thereto due to the superatmospheric pressure exerted on the combustion gases passing through the primary furnace space. This effect in combination with the additional heat transferred within the secondary furnace spaces results in an overall maximum thermal efficiency.

While preferred embodiments of the invention have been described for the purpose of disclosure, numerous changes in the details of construction and the arrangement of parts can be made which will readily suggest themselves to those skilled in the art. For example, the primary furnace space 11 and secondary furnace space 25 of the heater apparatus may be both formed of cylindrical shape and the heating tubes 18 and 28 may be continuous helical coils disposed therein. Such arrangements are encompassed within the spirit of the invention disclosed herein as defined by the appended claims.

What is claimed is:

l. in a fluid heater having walls defining a primary furnace space which includes a spent combustion gas outlet, a plurality of fluid heating tubes passing therethrough and one or more high intensity combustion burners attached to and positioned with respect to the furnace space so' that combustion gases produced by the burners are directed under super-atmospheric pressure into the furnace space and caused to circulate around the heating tubes thereby bringing about the transfer of heat from the combustion gases to the fluid being heated, the improvement which comprises:

walls defining a separate secondary furnace space having combustion gas inlet and outlet connections disposed therein;

a second plurality of heating tubes passing through said secondary furnace space;

conduit means connecting the first and second pluralities of heating tubes together so that the fluid being heated flows through the first plurality of heating tubes within the primary furnace space and then through the second plurality of heating tubes; and

means connecting between the spent combustion gas outlet of said primary furnace space and the combustion gas inlet of said secondary furnace space so that spent combustion gases exiting from the primary furnace space flow through the secondary furnace space under super-atmospheric pressure and additional heat is transferred from the spent combustion gases to the fluid being heated.

2. The heater apparatus of claim 1 wherein the means connecting between the combustion gas outlet of the primary furnace space and the combustion gas inlet of the secondary furnace space comprises at least one conduit connected therebetween.

3. The fluid heater apparatus of claim 2 which is further characterized to include one or more stacks connected to the combustion gas outlet of the secondary furnace space.

4. A fluid heater which comprises:

walls defining a primary furnace space having at least one spent combustion gas outlet connection disposed therein;

a first plurality of fluid heating tubes disposed in the primary furnace space;

at least one high intensity combustion burner attached to and positioned with respect to the primary furnace space so that combustion gases produced by the burner or burners are directed under super-atmospheric pressure into the primary furnace space and caused to circulate around the heating tubes disposed therein thereby bringing about the transfer of heat from the combustion gases to the fluid being heated;

walls defining a separate secondary furnace space having combustion gas inlet and outlet connections disposed therein;

a plurality of fluid heating tubes disposed within the secondary furnace space;

and means connecting between the spent combustion gas outlet of the primary furnace space and the combustion gas inlet of the secondary furnace space so that spent combustion gases'exiting from the primary furnace space flow through the secondary furnace space under super-atmospheric pressure and additional heat is transferred from the spent combustion gases to the fluid being heated.

5. The fluid heater apparatus of claim 4 which is further characterized to include at least one stack connected to the combustion gas outlet connection of the secondary furnace space.

6. The fluid heater apparatus of claim 5 which is further characterized to include:

walls defining a second secondary furnace space having combustion gas inlet and outlet connections disposed therein;

a third plurality of heating tubes disposed in said secondary furnace space;

conduit means connecting the third plurality of heating tubes to the first plurality of heating tubes dis- .posed within the primary furnace space so that the fluid being heated flows through the first plurality of heating tubes and then through the second and third pluralities of heating tubes; and

means connecting between the spent combustion gas outlet of said primary furnace space and the combustion gas inlet of the second secondary furnace space so that spent combustion gases from the primary furnace space flow through the second secondary furnace space and additional heat is transferred from the spent combustion gases to the fluid being heated.

7. The fluid heaterapparatus of claim 6 which is further characterized to include at least one stack connected to the combustion gas outlet connection of the 

1. In a fluid heater having walls defining a primary furnace Space which includes a spent combustion gas outlet, a plurality of fluid heating tubes passing therethrough and one or more high intensity combustion burners attached to and positioned with respect to the furnace space so that combustion gases produced by the burners are directed under super-atmospheric pressure into the furnace space and caused to circulate around the heating tubes thereby bringing about the transfer of heat from the combustion gases to the fluid being heated, the improvement which comprises: walls defining a separate secondary furnace space having combustion gas inlet and outlet connections disposed therein; a second plurality of heating tubes passing through said secondary furnace space; conduit means connecting the first and second pluralities of heating tubes together so that the fluid being heated flows through the first plurality of heating tubes within the primary furnace space and then through the second plurality of heating tubes; and means connecting between the spent combustion gas outlet of said primary furnace space and the combustion gas inlet of said secondary furnace space so that spent combustion gases exiting from the primary furnace space flow through the secondary furnace space under super-atmospheric pressure and additional heat is transferred from the spent combustion gases to the fluid being heated.
 2. The heater apparatus of claim 1 wherein the means connecting between the combustion gas outlet of the primary furnace space and the combustion gas inlet of the secondary furnace space comprises at least one conduit connected therebetween.
 3. The fluid heater apparatus of claim 2 which is further characterized to include one or more stacks connected to the combustion gas outlet of the secondary furnace space.
 4. A fluid heater which comprises: walls defining a primary furnace space having at least one spent combustion gas outlet connection disposed therein; a first plurality of fluid heating tubes disposed in the primary furnace space; at least one high intensity combustion burner attached to and positioned with respect to the primary furnace space so that combustion gases produced by the burner or burners are directed under super-atmospheric pressure into the primary furnace space and caused to circulate around the heating tubes disposed therein thereby bringing about the transfer of heat from the combustion gases to the fluid being heated; walls defining a separate secondary furnace space having combustion gas inlet and outlet connections disposed therein; a plurality of fluid heating tubes disposed within the secondary furnace space; and means connecting between the spent combustion gas outlet of the primary furnace space and the combustion gas inlet of the secondary furnace space so that spent combustion gases exiting from the primary furnace space flow through the secondary furnace space under super-atmospheric pressure and additional heat is transferred from the spent combustion gases to the fluid being heated.
 5. The fluid heater apparatus of claim 4 which is further characterized to include at least one stack connected to the combustion gas outlet connection of the secondary furnace space.
 6. The fluid heater apparatus of claim 5 which is further characterized to include: walls defining a second secondary furnace space having combustion gas inlet and outlet connections disposed therein; a third plurality of heating tubes disposed in said secondary furnace space; conduit means connecting the third plurality of heating tubes to the first plurality of heating tubes disposed within the primary furnace space so that the fluid being heated flows through the first plurality of heating tubes and then through the second and third pluralities of heating tubes; and means connecting between the spent combustion gas outlet of said primary furnace space and the combustion gas inlet of the second secondary furnace space so that spent combustion gases froM the primary furnace space flow through the second secondary furnace space and additional heat is transferred from the spent combustion gases to the fluid being heated.
 7. The fluid heater apparatus of claim 6 which is further characterized to include at least one stack connected to the combustion gas outlet connection of the secondary furnace space. 